For a century workers flocked to Dubuque, Iowa, as they raised new generations of laborers, they built houses, shops and streets that eventually covered over the Bee Branch Creek. The water gurgled through underground pipes out of sight and largely out of memory.

Until the rains came. On May 16, 1999, 5.6 inches of rain fell in 24 hours. The creek pipes and storm sewers overflowed, blowing out manhole covers and turning streets into chest-deep raging rivers. Hundreds of homes and businesses were flooded.